Simultaneously Applied Microbial Pesticides: Microbe-Microbe Interactions and Their Impact on Pathogen and Arthropod Pest Management

Victoria Deren, Tennessee State University


The purpose of these experiments was threefold. The first goal was to investigate twospotted spider mite behavioral response to plants treated with microbial miticides (Ancora & Grandevo) or microbial fungicides (RootShield Plus WP & Stargus). The second objective was to identify interactions between the microbial miticide, and fungicide products applied to control twospotted spider mite and Phytophthora root rot. In addition to these two central objectives, the impact of the microbial miticides on Swirski predatory mites was evaluated to ascertain the compatibility of these microbial and biological control agents. Experiments designed to answer these questions were conducted in laboratory and greenhouse settings. In arena studies, spider mites avoided ornamental pepper leaves treated with Ancora. Subsequent experiments were designed to further evaluate the plant foliage and the Ancora product. Through these experiments, the Ancora product itself was found to be repellent and not the treated leaves. Despite its repellent activity, Ancora was not toxic to spider mites when mites were confined to treated foliage. However, Grandevo, was toxic to both spider mites and their predator, Swirski mite. Despite the observed toxicity of Grandevo in laboratory trials, Swirski mite populations were able to survive under greenhouse conditions on ornamental pepper, indicating that these predatory mites and Grandevo are compatible in integrated pest management programs. Ancora was also compatible with Swirski mite in laboratory and greenhouse assays. When miticides and fungicides were applied to plants simultaneously, there was a consistent pattern of reduced efficacy of the microbial fungicides against Phytophthora root rot caused by Phytophthora capsici compared to the single applications of Stargus and RootShield Plus. The fungicide and miticide interference were especially common when fungicides were paired with Grandevo. Based on the patterns observed in the three greenhouse trials, temperature or other environmental factors likely impacted the establishment and overall efficacy of the microbial fungicides. Based on the results of these experiments, we would not recommend using more than one microbial product at a time. Further investigations are warranted to elucidate the mechanisms by which foliar and soil applied microbials interact and the consequences of those interactions on IPM program development.

Subject Area

Agriculture|Plant sciences

Recommended Citation

Victoria Deren, "Simultaneously Applied Microbial Pesticides: Microbe-Microbe Interactions and Their Impact on Pathogen and Arthropod Pest Management" (2020). ETD Collection for Tennessee State University. Paper AAI28153904.